Area Forecast Discussion
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070 FXUS62 KTAE 130806 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 406 AM EDT MON APR 13 2015 ...FLASH FLOOD WATCH CONTINUES FOR MUCH OF THE FLORIDA PANHANDLE TODAY... .NEAR TERM [THROUGH TODAY]...
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LAST EVENING, A SLOWLY MEANDERING HEAVY RAIN BAND WITH OCCASIONAL EMBEDDED THUNDERSTORMS PRODUCED PROLIFIC RAIN RATES IN WESTERN JACKSON COUNTY WITH STORM TOTAL AMOUNTS AS HIGH AS 11". AS OF 07 UTC, THAT PARTICULAR BAND OF RAIN HAS SINCE DIMINISHED, BUT A LARGER AREA OF RAIN AND EMBEDDED ISO-SCT THUNDERSTORMS IS ABOUT TO MOVE INTO OUR FORECAST AREA. ONE OF THE CONVECTIVE BANDS IN THAT LARGER AREA OF RAIN PRODUCED FLASH FLOODING AND OVER 7" OF RAIN IN THE MOBILE, ALABAMA AREA EARLIER. THE AREA OF RAIN IS SHIFTING EAST AHEAD OF A MID-LEVEL SHORTWAVE, AND ALSO COINCIDES WITH THE RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET STREAK. AS THE PRIMARY FORCING MECHANISMS APPEAR TO BE LARGER SCALE FEATURES, THIS AREA OF RAIN HAS BEEN MORE PROGRESSIVE FROM WEST TO EAST AND THEREFORE WE EXPECT IT TO TRANSITION ACROSS MUCH OF THE FORECAST AREA TODAY. POPS WERE BUMPED UP TO CATEGORICAL (80-90%) NORTHWEST OF A CAPE SAN BLAS, TO TALLAHASSEE, TO TIFTON LINE. HIGH TEMPERATURES WERE NUDGED DOWN INTO THE MID-70S NORTHWEST TO AROUND 80 SOUTHEAST DUE TO CLOUDS/RAIN. THE ENVIRONMENT AHEAD OF THE SHORTWAVE REMAINS LARGELY THE SAME AS WHEN WE SAW TORRENTIAL RAIN RATES NEAR MARIANNA (PWATS CLOSE TO RECORDS FOR MID APRIL, SLOW STORM MOTIONS, LOW RADAR ECHO CENTROIDS) AND THUS LOCALIZED HEAVY RAINFALL WILL REMAIN POSSIBLE - MAINLY NEAR THE COAST. HEAVY RAIN WORDING WAS INSERTED INTO THE FORECAST. IN THE WESTERN PANHANDLE (GENERALLY WEST OF THE APALACHICOLA RIVER), WHERE MORE RAIN FELL EARLIER WE HAVE POSTED A FLASH FLOOD WATCH UNTIL 20 UTC. RAIN RATES OF UP TO 3-4 INCHES PER HOUR WILL BE POSSIBLE ON ALREADY WET SOILS. THE WATCH MAY NEED TO BE ADJUSTED SPATIALLY OR TEMPORALLY DEPENDING ON HOW CONVECTION EVOLVES THIS MORNING. HOWEVER, GIVEN LIGHTER RAIN TOTALS OVER THE PAST 24 HOURS OUTSIDE THE WATCH AREA, SOILS MAY BE ABLE TO INITIALLY HANDLE HEAVY RAINFALL. .SHORT TERM [TONIGHT THROUGH WEDNESDAY]... UNSETTLED CONDITIONS WILL CONTINUE OVER THE AREA THROUGH THIS PERIOD. THE UPPER LOW OVER THE SOUTHERN PLAINS WILL OPEN UP AND EVENTUALLY BE ABSORBED BY AN APPROACHING LONG WAVE TROUGH. A DOWNSTREAM RIDGE WILL REMAIN IN PLACE OFF THE SOUTHEAST U.S. COAST. THIS WILL KEEP THE GULF COAST REGION UNDER WSW UPPER FLOW WITH RIPPLES OF ENERGY PASSING OVERHEAD FROM TIME TO TIME. A SYNOPTIC FRONT WILL LIFT NORTH OF THE REGION TONIGHT AND TUESDAY BEFORE SETTLING BACK TOWARD THE FORECAST AREA ON WEDNESDAY. PWAT WILL REMAIN WELL ABOVE NORMAL. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED THROUGH THE PERIOD. WHILE SEVERE WEATHER CHANCES ARE NOT ALL THAT HIGH, WE WILL NEED TO KEEP AN EYE ON THE FLASH FLOOD THREAT, ESPECIALLY AFTER SEEING WHAT THIS RATHER INNOCUOUS PATTERN PRODUCED OVER IN JACKSON COUNTY FL OVERNIGHT. BROAD RAINFALL TOTALS OF 2-2.5 INCHES ARE EXPECTED THROUGH WEDNESDAY NORTHWEST OF A LINE FROM PANAMA CITY TO ALBANY WITH TOTALS EXPECTED TO TAPER OFF TO THE SOUTHEAST. ABUNDANT CLOUDS WILL KEEP DAYTIME TEMPS LOWER THAN WHAT WE SAW FOR MUCH OF LAST WEEK. HOWEVER, THEY WILL REMAIN SEVERAL DEGREES ABOVE NORMAL WITH MAINLY LOWER TO MID 80S EXPECTED. OVERNIGHT LOWS WILL BE RUNNING SOME 15-18 DEGREES ABOVE NORMAL AND GENERALLY BE IN THE MID TO UPPER 60S. .LONG TERM [WEDNESDAY NIGHT THROUGH MONDAY]... THE UNSETTLED PATTERN WILL CONTINUE OVER THE AREA WITH TEMPERATURE AND HUMIDITY LEVELS REMAINING ABOVE SEASONAL LEVELS. ANOTHER UPPER LOW WILL EVENTUALLY MOVE FROM THE SOUTHERN ROCKIES OUT INTO THE PLAINS BY LATER IN THE WORK WEEK. THIS WILL PROMOTE A TENDENCY FOR RIDGING DOWNSTREAM OVER THE SOUTHEAST. A SURFACE FRONT WILL ALSO GENERALLY BE IN THE VICINITY OF THE GULF COAST STATES. TIMING INDIVIDUAL IMPULSES IN THE EL NINO-INDUCED FAST UPPER FLOW IN THE SOUTHERN STREAM, AND THEIR IMPACT ON THE EVOLUTION OF SURFACE FEATURES WILL BE TRICKY, SO WHILE DETAILS ARE UNCLEAR, A CONSENSUS FOR HIGHER THAN CLIMO POPS AND TEMPS CONTINUES.
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&& .AVIATION...
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[THROUGH 06Z TUESDAY] SOME LOW CIGS ARE LIKELY THIS MORNING AT MOST OF THE TERMINALS, DOWN INTO THE IFR-LIFR RANGE AT TIMES. HOWEVER, SLOW IMPROVEMENT IS EXPECTED LATER THIS MORNING AND INTO THE AFTERNOON WITH A TREND TOWARD MVFR-VFR CIGS. AN AREA OF RAIN AND EMBEDDED ISOLATED THUNDERSTORMS WILL CONTINUE TO BUILD INTO THE AREA, WITH ALL TERMINALS LIKELY TO SEE RAIN AT SOME POINT. VIS MAY BE REDUCED AT TIMES IN HEAVIER RAIN.
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&& .MARINE...
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OUTSIDE OF THUNDERSTORMS, RELATIVELY LIGHT WINDS AND LOW SEAS WILL PREVAIL FOR THE NEXT SEVERAL DAYS.
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&& .FIRE WEATHER...
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RED FLAG CONDITIONS ARE NOT EXPECTED WITH HIGH RH EXPECTED TO PREVAIL OVER THE NEXT SEVERAL DAYS. WETTING RAINS ARE LIKELY AND FUEL MOISTURE LEVELS SHOULD STAY HIGH.
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&& .HYDROLOGY...
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EXCEPTIONAL RAINFALL TOTALS OCCURRED OVERNIGHT IN WESTERN JACKSON COUNTY AND ADJACENT AREAS. EOX AND TLH RADAR BOTH SHOW A BROAD AREA WITH AT LEAST 2-3" ACCUMULATIONS, AND MAXIMUM VALUES AS HIGH AS 11" NEAR COTTONDALE AS OF 07 UTC. THIS WAS CONFIRMED BY A PUBLIC REPORT OF AROUND 11" IN THAT SAME AREA. THEREFORE, THE ENVIRONMENT TODAY AND INTO THE WEEK WILL FAVOR THE POSSIBILITY OF VERY HEAVY RAIN RATES IN SLOW MOVING SHOWERS AND STORMS. SOME LOCALIZED FLOODING WILL BE POSSIBLE DEPENDING ON WHERE HEAVIER BANDS OF RAIN AND/OR STORMS SET UP. BY WEDNESDAY AFTERNOON, WE ARE EXPECTING A BROAD AVERAGE OF 1 TO 3 INCHES OF RAIN ACROSS THE AREA, WITH SLIGHTLY LOWER AMOUNTS IN THE EASTERN FLORIDA BIG BEND. RAINFALL AMOUNTS THIS HIGH SHOULD CAUSE FLOWS TO INCREASE ON AREA RIVERS WITH THE POSSIBILITY OF A FEW REACHING FLOOD STAGE. IN PARTICULAR, THE CHIPOLA RIVER WILL NEED TO BE MONITORED GIVEN THE AFOREMENTIONED HEAVY RAINFALL IN THE UPPER PORTION OF THE BASIN.
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&& .PRELIMINARY POINT TEMPS/POPS...
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TALLAHASSEE 79 69 85 68 83 / 80 40 60 30 60 PANAMA CITY 76 71 80 70 78 / 80 50 60 40 60 DOTHAN 76 66 83 66 82 / 80 50 70 50 70 ALBANY 77 66 85 67 82 / 80 50 70 40 60 VALDOSTA 81 66 85 66 84 / 70 40 60 30 60 CROSS CITY 83 67 85 67 84 / 60 40 40 20 50 APALACHICOLA 77 73 82 72 81 / 60 40 50 30 50
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&& .TAE WATCHES/WARNINGS/ADVISORIES...
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FL...FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR CALHOUN-CENTRAL WALTON-COASTAL BAY-HOLMES-INLAND BAY-JACKSON-NORTH WALTON- SOUTH WALTON-WASHINGTON. GA...NONE. AL...NONE. GM...NONE.
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&& $$ NEAR TERM...LAMERS SHORT TERM...WOOL LONG TERM...WOOL AVIATION...LAMERS MARINE...WOOL FIRE WEATHER...LAMERS HYDROLOGY...LAMERS

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